Start by preparing the caramel sauce. In a small saucepan, combine all the sauce ingredients together and bring to a boil. Continue boiling until the sugar is totally dissolved.

Heat the vegetable oil in a wok or large, deep frying pan over high heat, until just smoking. Add the garlic and onion and stir-fry until golden,

Add the shrimp, pepper, 2 tablespoons of the caramel sauce and the chili oil and cook until the sauce is thick enough to coat the shrimps, about 2 minutes. Reserve any remaining caramel sauce for later use.

Add the green onions and stir-fry the whole thing for about 30 seconds longer. Serve at once, on a bed of lettuce, if desired.